diff --git a/Resample/FFCompute/IComputeFF.cpp b/Resample/FFCompute/IComputeFF.cpp
index e13c607f6dbda5d5e46b799c7c0bcbf715532425..a956ecbe9ea2e61e7543274f50cca81d76262eda 100644
--- a/Resample/FFCompute/IComputeFF.cpp
+++ b/Resample/FFCompute/IComputeFF.cpp
@@ -26,11 +26,6 @@ IComputeFF::IComputeFF(const IFormFactor& ff, size_t iLayer)
 
 IComputeFF::~IComputeFF() = default;
 
-void IComputeFF::setAmbientMaterial(const Material& material)
-{
-    m_ff->setAmbientMaterial(material);
-}
-
 double IComputeFF::volume() const
 {
     return m_ff->volume();
diff --git a/Resample/FFCompute/IComputeFF.h b/Resample/FFCompute/IComputeFF.h
index 23347ae46514b7b20da1cfe3113e3bb63858cc8b..37af6e80c48cc4ec563f46584e6bc94ae32df95c 100644
--- a/Resample/FFCompute/IComputeFF.h
+++ b/Resample/FFCompute/IComputeFF.h
@@ -42,8 +42,6 @@ public:
     virtual ~IComputeFF();
     virtual IComputeFF* clone() const = 0;
 
-    virtual void setAmbientMaterial(const Material& material);
-
     size_t iLayer() const { return m_iLayer; }
 
     virtual double volume() const;
@@ -62,7 +60,7 @@ public:
 protected:
     IComputeFF(const IFormFactor& ff, size_t iLayer);
 
-    std::unique_ptr<IFormFactor> m_ff;
+    std::unique_ptr<const IFormFactor> m_ff;
     const size_t m_iLayer;
 };